1. Field of the Invention
The present invention relates generally to a multitube catheter assembly, and more particularly to a multitube catheter assembly comprising one or more pressure resistant lumens.
2. Description of the Prior Art
(A) Technical Background
Catheters for the introduction or removal of fluids may be located in various venous locations and cavities throughout the body for the introduction or removal of fluids. Such catheterization may be performed by using a single catheter having multiple lumens.
Generally, to insert any catheter in a blood vessel, the vessel is identified by aspiration with a long hollow needle in accordance with the Seldinger technique. When blood enters a syringe attached to the needle, indicating that the vessel has been found, a thin guide wire is then introduced, typically through a syringe needle or other introducer device, into the interior of the vessel. The introducer device is then removed leaving the guide wire within the vessel. The guide wire projects beyond the surface of the skin.
At this point, several options are available to a physician for catheter placement. The simplest is to pass a catheter into the vessel directly over the guide wire. The guide wire is then removed leaving the catheter in position within the vessel. However, this technique is only possible in cases where the catheter is of a relatively small diameter, made of a stiff material and not significantly larger than the guide wire, for example, for insertion of small diameter dual lumen catheters. If the catheter to be inserted is significantly larger than the guide wire, a dilator device is first passed over the guide wire to enlarge the hole. The catheter is then passed over the guide wire, and the guide wire and dilator are removed.
A central venous catheter (“central line”) is a catheter placed within a large vein in the neck, chest, or groin. It is generally used to administer chemotherapeutic agents or other IV medications or fluids and to obtain blood tests and measurements. The overall safety and use of conventional and commercially available central venous catheters for these indications is well known. However, nearly twenty percent of central line recipients also require a CT scan. Although these patients frequently undergo IV contrast-enhanced CT as part of their clinical examination and follow-up, the feasibility and safety of using central venous catheters to administer IV contrast material using a power injector has not been well established. Because many patients requiring central venous catheters have poor peripheral IV access, it is both practical and often necessary to administer IV contrast material through the central venous catheter. Such administration is also more convenient for the patient.
The viscosities of the contrast media required in procedures such as a CT with contrast are high and an amount of up to 200 ml may be needed to be injected in a very short period of time. In general, consistent vascular enhancement and high levels of hepatic enhancement can be achieved when rapid infusion rates and appropriate delay times are used.
U.S. Pat. No. 6,524,302 issued to Kelley describes a multi-lumen catheter and method of manufacturing same in which the catheter comprises a plurality of individual catheter tubes. Each catheter tube has an outer surface, an inner surface and a lumen. The catheter tubes can be made of different thermoplastic materials. A mandrel is first inserted into the lumen of each catheter tube to provide support. The catheter tubes are then juxtaposed to each other in an arrangement. The outer surface of one catheter tube is in contact with the outer surface of at least one other catheter tube in the arrangement. The arrangement of catheter tubes is then held in a sleeve and is advanced through the sleeve, and through a heating cylinder to fuse the outer surfaces of the catheter tubes. A cooling means is placed in the lumen of each catheter tube to prevent the inner surface of each catheter tube from melting. Kelley teaches a catheter tube bundle formed by the fusing of the individual catheter tube material.
The Kelley bundle does not have a generally circular outside configuration. Also, the individual tubes that comprise the Kelley catheter tube bundle are fused with one another in such a manner as to result in the presence of fused material between each individual tube. However, the Kelley fused material to these spaces and does not extend to the areas, for example, where the individual catheter tubes do not meet. Therefore, Kelley provides for a fused bundle with a shape that conforms to the number of individual catheter tubes employed. For example, when three tubes are used, the fused bundle has a clover leaf shape. When two tubes are used, the fused bundle has a figure eight shape. Kelley does not teach a way to control the surface or the size of the resulting fused tube as the cross-section of the Kelley multilumen catheter has an outer periphery with at least three distinct lobes, each lobe corresponding to one of the fused tubes and not a circular outer surface configuration. Also, an additional lumen is created from the outer surfaces of the three fused catheter tubes.
(B) Manufacturing Background
U.S. Pat. Publication No. 2003/0153898 (“Schon”) teaches methods for making a multilumen catheter. The methods include forming a unitary catheter tube having a proximal portion, a distal portion, and a distal end portion terminating in a distal end tip. The unitary catheter tube may be formed using any suitable heat molding process, including injection molding, expansion/compression molding, and extrusion. The unitary catheter tube is formed by extrusion through a die to form internal lumens; the lumens are substantially identical in size, configuration, and materials. The unitary catheter tube, with internal longitudinally extending lumens, may also be formed by injection molding the tube around metal rods which have the shape of the internal lumens.
However, the methods and catheters taught by Schon do not provide a fused catheter bundle with a pressure resistant lumen with circular lumens and outside configuration.
U.S. Pat. No. 6,190,349 (“Ash”) teaches a multiple catheter assembly having an outer surface defining a first lumen. A second catheter has an outer surface defining a second lumen extending through the full length of their respective catheters. The lumens each have a generally semi-circular cross section. Accordingly, the first catheter has an outer surface defined by a rounded wall portion and a generally flat side surface, and the second catheter also has an outer surface defined by a rounded wall portion and a generally flat side surface, as viewed in cross section. The flat side surfaces face each other.
However, the methods and catheters taught by Ash do not provide a fused catheter bundle with a pressure resistant lumen with circular lumens and outside configuration.
There exists a need for a fused multiple catheter assembly and a method for manufacturing same, which is suitably flexible, easily inserted and which will reduce the potential risk of leakage at the site of vessel entry, but which will still maintain some of the original properties of the individual catheter tubes with respect to independent movement within a vessel, good flow properties, and pressure resistance.
Generally, the multilumen catheter design of the present invention, due to its rounded inner lumen, decreases the resistance effect to the flow of fluids, including a particularly viscid material such as contrast media. The multilumen design presented herein produces higher flow rates. Moreover, one of the fused tubes is made from a higher grade material, such as PEBA, that will resist higher internal pressure and result in a pressure resistant lumen. The higher laminar flow rate and resistance to pressure make the catheter suitable for the powerful injection of contrast media where flow may be needed at a rate of up to 10 ml/sec. A catheter constructed in accordance with the present disclosure with two tubes of different hardness levels, lowers the overall catheter rigidity than if it the catheter were totally made from the harder material which is much safer and comfortable for the patients.